Search

In this work, a biologically catalyzed CO 2 mineralization process for the capture of CO 2 from point sources was designed, constructed at a laboratory scale, and, using standard chemical process scale-up protocols, was modeled and evaluated at an industrial scale. A yeast display system in Saccharomyces cerevisae was used to screen several carbonic anhydrase isoforms and mineralization peptides for their impact on CO 2 hydration, CaCO 3 mineralization, and particle settling rate. Enhanced rates for each of these steps in the CaCO 3 mineralization process were confirmed using quantitative techniques in lab-scale measurements. The effect of these enhanced rates on the CO 2 capture cost in an industrial scale CO 2 mineralization process using coal fly ash as the CaO source was evaluated. The model predicts a process using bCA2- yeast and fly ash is ~10% more cost effective per ton of CO 2 captured than a process with no biological molecules, a savings not realized by wild-type yeast and high-temperature stable recombinant CA2 alone or in combination. The levelized cost of electricity for a power plant using this process was calculated and scenarios in which this process compares favorably to CO 2 capture by MEA absorption process are presented.

A pillar[5]arene-modified polydopamine (PDA-P[5]OH) displaying pH/NIR dual-responsive properties was constructed successfully in situ for targeted chemo-photothermal cancer therapy. [ABSTRACT FROM AUTHOR]

Pressurized techniques are straightforward for high-scale applications and highly controllable, which seems an excellent strategy for recovering unstable natural compounds. In this work, the main advance was the development of a platform based on the pressurized liquid extraction coupled in-line with a solid-phase extraction step (PLE-SPE) combined with the use of eutectic mixtures as solvents to promote an efficient extraction and purification of natural pigments from food wastes. Eutectic mixtures, conventionally known as (deep) eutectic solvents - (D)ES, are combinations of two or more substances with a lower melting point than any of their components. (D)ES are often referred as "green solvents" because they can potentially be more environmentally friendly than other solvents, especially volatile organic solvents (VOSs). Overall, (D)ES have the potential to contribute to the achievement of several of the SDGs (especially 3, 13, and 14) through their positive impacts on health, environment, and sustainable production and consumption practices. Thus, in this work, (D)ES were used as solvents to valorize Brazilian berry waste (Plinia cauliflora). Anthocyanins are the biomass's main compounds of commercial interest, mainly for food and cosmetic applications. However, there are several technological issues regarding color control due to their high sensitivity to light, heat, oxygen, and pH variations. Thus, the data achieved in this work highlighted the high efficiency and low environmental footprint of the PLE-SPE-(D)ES platform developed. The success of the downstream process here developed was proved by the high extraction efficiency and the purity level of the anthocyanins obtained. Besides, thermal stability analysis was evaluated, demonstrating that (D)ES are not only solvents but also stabilizing agents, improving the shelflife of the extracted colorants. [ABSTRACT FROM AUTHOR]

Direct C–H bond arylation of (hetero)arenes is a very convenient approach for the synthesis of a wide variety of molecular targets, including compounds of pharmaceutical interest and π-conjugated small molecules and polymers. Compared to traditional transition metal-promoted cross-coupling reactions, direct C–H arylations best fit the Green Chemistry criteria, particularly in minimization of waste, use of less hazardous chemicals, atom economy, and reduction of unnecessary derivatization steps. Despite the advantages, these reactions still initially suffered from major limitations in terms of sustainable chemistry, i.e., toxic and expensive transition-metal catalysts, toxic and/or hazardous solvents, high temperatures and long reaction times. The increasing attention towards environmentally friendly reaction protocols has boosted studies directed towards the development of sustainable strategies for direct C–H bond arylation of (hetero)arenes. This review offers a critical overview of the research on this topic, focusing on three main aspects: (i) recoverable catalysts; (ii) sustainable solvents; (iii) non-conventional energy sources. [ABSTRACT FROM AUTHOR]

In this work, an in situ dielectric barrier discharge trap (DBDT) was first utilized to preconcentrate inorganic arsenic (iAs) species coupled with liquid chromatography hydride generation atomic fluorescence spectrometry (LC-HG-AFS), and a novel LC-HG-in situ DBDT-AFS instrument was thereby fabricated. Considering the relatively deficient sensitivity of LC-HG-AFS and retention of As(V) in a strong anion exchange column, As(V) was chosen as a model species for iAs preconcentration. During the extraction of arsenic species in a rice sample using 1% (v/v) HNO3 and 1% (v/v) H2O2, As(III) was oxidized to As(V) being regarded as iAs. After LC separation, according to the retention time, only As(V) was trapped by 11 kV discharging under 110 mL min−1 air mixed with Ar; following sweeping by Ar gas for 190 s, iAs was released with 13 kV at 180 mL min−1 H2-rich Ar to the AFS for measurement. Via preconcentration, the limit of detection (LOD) of iAs reached 0.05 μg L−1 with ∼10 times enhancement in analytical sensitivity; the linearity (r) was > 0.997 ranging from 0.5 μg L−1 to 50 μg L−1 with 1.9% RSD (5 μg L−1, n = 6). The measured iAs in certified reference materials (CRMs) were all within their certified values, and the spike recoveries were in the range of 93–102%. With sensitivity, robustness, low power, small size and easy operation, the combination of LC and DBDT fulfilled the analysis of trace iAs in rice samples. In fact, other arsenic species can also be preconcentrated and detected to enhance the sensitivity by this proposed LC-HG-in situ DBDT technique via precisely synchronizing DBD trap and release with chromatographic retention. To focus on the food safety, iAs was chosen as a model arsenic species to verify the availability of in situ DBDT. Considering the versatility of DBD, in situ DBDT demonstrates a promising application for elemental speciation analysis and LC atomic spectrometry. [ABSTRACT FROM AUTHOR]

Relevant papers in the field of arsenic speciation analysis of environment samples published between 2004 and 2018 have been reviewed, with the focus on the analytical procedures according to the matrix investigated and the species researched. It emerged that suitable analytical methods have been developed for the identification and quantification of about fifty arsenic compounds in the main environmental matrices, including soil, sediments, terrestrial and marine organisms, atmospheric particulate and various types of natural waters. Various extraction/partitioning schemes have been applied, depending on the arsenic species (water- or lipid-soluble) and the matrix (biotic or abiotic), whereas water samples were generally analyzed directly. Liquid chromatography (LC) combined with inductively coupled plasma mass spectrometry was by far the analytical technique of choice, but a significant number of works also applied other couplings (LC to further atomic and mass spectrometry techniques) or X-ray methods. By the application of these procedures, a great amount of information on the occurrence of arsenic in the environment has been obtained, as well as the elucidation of the main processes involved and the discovery of new compounds, like arsenolipids and thio-arsenicals. However, remaining gaps and challenges still exist, both in the fundamental research on the origin and transformation of arsenic compounds in various environmental compartments and in the routine monitoring of toxic arsenic species. It is hence likely that the attempt to address these issues will drive the future research in the field. [ABSTRACT FROM AUTHOR]

The development of carbohydrate-binding ligands is crucial for expanding knowledge on the glycocode and for achieving systematic carbohydrate targeting. Amongst such ligands, carbohydrate-binding peptides (CBPs) are attractive for use in bioanalytical and biomedical systems due to their biochemical and physicochemical properties; moreover, given the biological significance of lectin–carbohydrate interactions, these ligands offer an opportunity to study peptide sequence and binding characteristics to inform on natural target/ligand interactions. Here, a high-throughput microarray screening technique is described for the identification and study of CBPs, with a focus on polysialic acid (PSA), a polysaccharide found on neural stem cells. The chemical and biological uniqueness of PSA suggests that an ability to exclusively target this glycan may promote a number of diagnostic and therapeutic applications. PSA-binding peptides from phage display screening and from epitope mapping of an scFv for oligosialic acid were screened in an optimized microarray format with three ligand density conditions. Hypothesis-driven mutations were additionally applied to select peptides to modulate peptide affinity and selectivity to PSA. Peptide compositional and positional analyses revealed the significance of various residues for PSA binding and suggested the importance of basic residue positioning for PSA recognition. Furthermore, selectivity studies performed directly on microarrays with chondroitin sulfate A (CS-A) demonstrated the value of screening for both affinity and selectivity in the development of CBPs. Thus, the integrated approach described, with attention to design strategy, screening, and peptide characterization, successfully identified novel PSA-binding ligands and offers a platform for the identification and study of additional polysaccharide-binding peptides. [ABSTRACT FROM AUTHOR]

Topographical patterning has recently attracted lots of attention in regulating cell fate, understanding the mechanism of cell–microenvironment interactions, and solving the great issues of regenerative medicine. The introduced patterns offer topographical cues that can affect the reconstruction of the cytoskeleton or stimulate cell membrane receptors. Numerous studies have focused on these effects on cell behavior including attachment, migration, proliferation, and differentiation. In this review, five aspects of topographical patterning are discussed: (1) the process of typical micro-/nanotechniques and their advantages and limitations; (2) the effects of patterning on the mechanical properties and surface properties of substrates; (3) the influences of micro-/nanopatterns on the behavior of mesenchymal stem cells, as well as the underlying mechanisms; (4) the application of patterns to solve the issues of targeted organs (e.g., skin, nerves, blood vessels, bones, and heart). In the end, future perspectives that would help promote the efficiency of topographical patterning are proposed. [ABSTRACT FROM AUTHOR]

Cancer is currently one of the world's most serious public health problems. Significant efforts are being made to develop new strategies that can eradicate tumours selectively without detrimental effects to healthy cells. One promising approach is focused on the design of vaccines that contain partially glycosylated mucins in their formulation. Although some of these vaccines are in clinical trials, a lack of knowledge about the molecular basis that governs the antigen presentation, and the interactions between antigens and the elicited antibodies has limited their success thus far. This review focuses on the most significant milestones achieved to date in the conformational analysis of tumour-associated MUC1 derivatives both in solution and bound to antibodies. The effect that the carbohydrate scaffold has on the peptide backbone structure and the role of the sugar in molecular recognition by antibodies are emphasised. The outcomes summarised in this review may be a useful guide to develop new antigens for the design of cancer vaccines in the near future. [ABSTRACT FROM AUTHOR]

Electrochemical capacitors (i.e. supercapacitors) include electrochemical double-layer capacitors that depend on the charge storage of ion adsorption and pseudo-capacitors that are based on charge storage involving fast surface redox reactions. The energy storage capacities of supercapacitors are several orders of magnitude higher than those of conventional dielectric capacitors, but are much lower than those of secondary batteries. They typically have high power density, long cyclic stability and high safety, and thus can be considered as an alternative or complement to rechargeable batteries in applications that require high power delivery or fast energy harvesting. This article reviews the latest progress in supercapacitors in charge storage mechanisms, electrode materials, electrolyte materials, systems, characterization methods, and applications. In particular, the newly developed charge storage mechanism for intercalative pseudocapacitive behaviour, which bridges the gap between battery behaviour and conventional pseudocapacitive behaviour, is also clarified for comparison. Finally, the prospects and challenges associated with supercapacitors in practical applications are also discussed. [ABSTRACT FROM AUTHOR]

Nanogels are nanosized crosslinked polymer networks capable of absorbing large quantities of water. Specifically, smart nanogels are interesting because of their ability to respond to biomedically relevant changes like pH, temperature, etc. In the last few decades, hybrid nanogels or composites have been developed to overcome the ever increasing demand for new materials in this field. In this context, a hybrid refers to nanogels combined with different polymers and/or with nanoparticles such as plasmonic, magnetic, and carbonaceous nanoparticles, among others. Research activities are focused nowadays on using multifunctional hybrid nanogels in nanomedicine, not only as drug carriers but also as imaging and theranostic agents. In this review, we will describe nanogels, particularly in the form of composites or hybrids applied in nanomedicine. [ABSTRACT FROM AUTHOR]

Complexes [Cu(i)(2,4-dimethylphenoxy)2]− (A) and [Cu(ii)(2,4-dimethylphenoxy)2(p-tolyl)]− (B) were observed by in situ electrospray ionization mass spectrometry (ESI-MS) analysis of the ligand free copper(i)-catalyzed C–O coupling reaction using Cs2CO3 under the catalytic reaction conditions indicating that they could be intermediates in the reaction. The radical scavenger cumene retarded the reaction. Catalytic cycles involving a free radical path are proposed based on these observations. [ABSTRACT FROM AUTHOR]

The C-O coupling reaction between 2,4-dimethylphenol and 4-bromotoluene catalyzed by the CuI/ K2CO3/phen system can be inhibited by the radical scavenger cumene. Complexes [Cu(I)(phen)(1-(2,4- dimethylphenoxy)-4-methylbenzene)]+ (denoted as A), {H[Cu(I)(phen)(2,4-dimethylphenoxy)]}+ and [Cu(I)(2,4-dimethylphenoxy)2]- (denoted as B) were observed by in situ electrospray ionization mass spectrometry (ESI-MS) analysis of the copper(I)-catalyzed C-O coupling reaction under the catalytic reaction conditions indicating that they could be intermediates in the reaction. The in situ EPR study of the reaction solution detected the Cu(II) species with a fitted g value of 2.188. A catalytic cycle with a single electron transfer (SET) step was proposed based on these observations. [ABSTRACT FROM AUTHOR]

Cu-catalysed arylation reactions devoted to the formation of C-C and C-heteroatom bonds (Ullmanntype couplings) have acquired great importance in the last decade. This review discusses the history and development of coupling reactions between aryl halides and various classes of nucleophiles, focusing mostly on the different mechanisms proposed through the years. Selected mechanistic investigations are treated more in depth than others. For example, evidence in favour or against radical mechanisms is discussed. Cu(I) and Cu(III) complexes involved in the Ullmann reaction and N/O selectivity in aminoalcohol arylation are discussed. A separate section has been dedicated to the synthesis of heterocyclic rings through intramolecular couplings. Finally, recent developments in green chemistry for these reactions, such as reactions in aqueous media and heterogeneous catalysis, have also been reviewed. [ABSTRACT FROM AUTHOR]

This is the fifth Atomic Spectrometry Update (ASU) to focus specifically on developments in elemental speciation and covers a period of approximately 12 months from January 2012. The International Union for Pure and Applied Chemistry (IUPAC) have evaluated speciation and provided a definition as follows: “speciation analysis is the analytical activity of identifying and/or measuring the quantities of one or more individual chemical species in a sample; the chemical species are specific forms of an element defined as to isotopic composition, electronic or oxidation state, and/or complex or molecular structure; the speciation of an element is the distribution of an element amongst defined chemical species in a system”. This review therefore deals with all aspects of the analytical speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. As with all ASU reviews1–5 the coverage of the topic is confined to those methods that incorporate atomic spectrometry as the measurement technique. However, in the spirit of meeting the needs of the subject, material is incorporated that is not strictly “atomic spectrometry”. For the most part, such procedures are those in which some form of molecular MS is used for speciation measurements, often in parallel with an elemental detector. As the content of this Update shows, the field is now maturing as evidenced by the extent to which the speciation of particular elements or technique combinations have been the subject of review articles. However, it is becoming increasingly difficult to ascertain the analytical details of the methodologies applied in speciation analysis, particularly where the paper is published in an ‘application’ based journal. [ABSTRACT FROM AUTHOR]

The role of the electrode nanoporosity in electroanalytical processes is discussed and specific phenomena (slow double layer charging, local pH effects) which can be present in porous electrode are described. Hierarchical porous carbon (HPC) materials are synthesized using a hard template method. The three dimensional carbon porosity is examined using scanning electron microscopy on flat surfaces cut using a focused ion beam (FIB-SEM). The electrochemical properties of the HPC are measured using cyclic voltammetry, AC impedance, chronoamperometry and Probe Beam Deflection (PBD) techniques. Chronoamperometry measurements of HPC seems to fit a transmission line model. PBD data show evidence of local pH changes inside the pores, during double layer charging. The HPC are modified by in situ (chemical or electrochemical) formation of metal (Pt/Ru) or metal oxide (CoOx, Fe3O4) nanoparticles. Additionally, HPC loaded with Pt decorated magnetite (Fe3O4) nanoparticles is produced by galvanic displacement. The modified HPC materials are used for the electroanalysis of different substances (CO, O2, AsO3−3). The role of the nanoporous carbon substrate in the electroanalytical data is evaluated. [ABSTRACT FROM AUTHOR]

Arsenobetaine is one of the major organoarsenic compounds found in aquatic organisms, including seafood and fish meant for human consumption. It has been widely studied over the last 50 years because of its non-toxic properties, and its origin is postulated to be at bottom of the aquatic food chains. The present review focuses on arsenobetaine formation in marine and freshwater plankton, comparing the arsenic compounds found in the different plankton organisms, and the methods used to assess arsenic speciation. The main findings indicate that in the marine environment, phytoplankton and micro-algae contain arsenosugars, with the first traces of arsenobetaine appearing in herbivorous zooplankton, and becoming a major arsenic compound in carnivorous zooplankton. Freshwater plankton contains less arsenobetaine than their marine relatives, with arsenosugars dominating. The possible role and formation pathways of arsenobetaine in plankton organisms are reviewed and the literature suggests that arsenobetaine in zooplankton comes from the degradation of ingested arsenosugars, and is selectively accumulated by the organism to serve as osmolyte. Several arsenic compounds such as arsenocholine, dimethylarsinoylacetate or dimethylarsinoylethanol that are intermediates of this pathway have been detected in plankton. The gaps in research on arsenobetaine in aquatic environments are also addressed: primarily most of the conclusions are drawn on culture-based experiments, and few data are present from the natural environment, especially for freshwater ecosystems. Moreover, more data on arsenic in different zooplankton species would be helpful to confirm the trends observed between herbivorous and carnivorous organisms. [ABSTRACT FROM AUTHOR]

Fast scan cyclic voltammetry (FSV) with a nanostructured carbon fiber sensor (N-CFS) was developed for direct measurements of the purine metabolite 2,8-dihydroxyadenine (2,8-DHA; i.e.6-amino-1H-purine-2,8-dione) in endothelial cell supernatants as a marker of cell stress. The 2,8-DHA was measured in the supernatant of aortic (AECs) and pulmonary artery endothelial cells (PAECs), which were maintained in Hank's Balanced Salt solution (HBSS) and exposed to physiological oxygen pressures as well as to oxidative stress, hypoxia (specifically 3% O2for AECs) and hyperoxia (20% O2for PAECs). Dilution of the supernatants with phosphate buffer in the ratio of 1 : 5 allowed the optimization of FSV measurements with the N-CFS in cell supernatants.The LOD for 2,8-DHA was 1 μM and the LDR was 2–15 μM with the sensitivity of (0.34 ± 0.01) nA μM−1(R2= 0.99). The changes in 2,8-DHA concentration when the cells were exposed to stress confirm that PAECs can adapt to stress. However, the results also show that the tolerance of AECs to hypoxia is low. Cellular pathways involved in the response of PAECs and AECs to oxidative stress are outlined. [ABSTRACT FROM AUTHOR]

High selectivity and sensitivity is reported in the measurements of xanthine in urine by fast scan cyclic voltammetry (FSV) with a nanostructured carbon fiber sensor of 3.5 ± 0.4 μm radius. Fabrication of the sensors for the measurements is described. Fabrication of the nanostructure at the carbon fiber sensor surface exposes surface pores. SEM images confirm the formation of the nanostructure. The results indicate that the nanostructure improves the sensitivity and limit of detection (LOD) in the measurements of xanthine and uric acid. The sensors allow rapid direct measurements of xanthine in 2000-fold diluted xanthinuric urine and of uric acid in 2000-fold diluted normal urine. The sensitivity and the LOD of xanthine is 0.40 ± 0.02 nA μM−1(0.995) and 1 μM, respectively, and 0.99 ± 0.01 nA μM−1(0.998) and 500 nM for uric acid. The concentration of xanthine in 2000-fold diluted xanthinuric urine is 1.6 ± 0.2 μM from FSV and from HPLC. The concentration of xanthine and uric acid in urine can be determined by pre- or post-calibration of the sensor in buffer or by the method of standard addition. [ABSTRACT FROM AUTHOR]

An admixture of zinc(II)-bis(dipicolylamine) receptor with covalently attached paramagnetic relaxation agent and fluorine-labeled phosphate indicator enables 19F NMR detection of phosphorylated analytes with amplified switched-on signal intensity. [ABSTRACT FROM AUTHOR]